Structure Tuning And Properties Of Platinum Monolayer Nano-electrocatalyst For Fuel Cells

Direct alcohol fuel cell(DAFC)is a sort of fuel cell using small molecule alcohols such as methonal and ethanol as fuel,and oxygen in air as oxidant.While Hydrogen-oxygen fuel cell suffers from inconvenience of hydrogen storage and transportation,DAFC has been widely focused.However,the oxidation kinetics of methaol and ethanol is sluggish,so highly effective and stable anodic catalysts is needed.Platimum shows the best activity to alcohol oxidation among all the noble metals,but it’s easy inactivation by strongly adsorbing CO intermediate,along with high cost,impede the large-scale application.Thus it is of practical significance to develop novel catalysts to promote utilization and CO resistance of Pt.Pt monolayer on a second metal substrate is considered to be an effective method with ideally 100% Pt utilization.But recent researches contradict in the real structure of Pt monolayer,especially in Pt monolayer on gold.Focusing on this phenomenon,the major concepts and results of this thesis are as listed below:First,by depositing Pt monolayer on different metal substrate(Pd,Ir,Pt,Au)using Cu UPD + galvanic replacement,it is found that Pt is not apt to form clusters on substrate interacting strongly with Pt(Pd,Ir,Pt).Substrate-induced tensile strain of Pt overlayer enhances catalytic activities for alcohol oxidation(Au),vice versa.Second,Pt(sub)monolayers with different nominal Pt coverage are deposited on Au using Cu UPD + galvanic replacement.At low nominal coverage,Pt more resembles(sub)monolayer.As nominal coverage increases,nanoislands with thickness of several atoms are formed,reducing the Pt utilization.Accordingly,in methanol oxidation reaction(MOR),the increase of catalytic activitiy is obvious till nominal coverage reaches 0.5 monolayer and slows down afterwards.Therefore Au@Pt0.5ML catalyst is considered to be more appropriate than conventional Au@Pt1ML catalyst.Last,by depositing Pt monolayer using Cu UPD + galvanic replacement on Cu/Au core-shell nanoparticles obtained by chemical corrosion,sandwich-structured Cu/Au/Pt catalyst is synthesized.Compared with Au@Pt catalyst,Pt overlayer on Cu/Au more resembles monolayer,obvious increase in ECSA and mass activities are observed.